Fa N, Lins L, Courtoy P J, Dufrêne Y, Van Der Smissen P, Brasseur R, Tyteca D, Mingeot-Leclercq M-P
Université Catholique de Louvain, Unité de Pharmacologie Cellulaire et Moléculaire, Avenue E. Mounier 73, Bt 7370, B-1200 Brussels, Belgium.
Biochim Biophys Acta. 2007 Jul;1768(7):1830-8. doi: 10.1016/j.bbamem.2007.04.013. Epub 2007 Apr 24.
The elastic properties of membrane bilayers are key parameters that control its deformation and can be affected by pharmacological agents. Our previous atomic force microscopy studies revealed that the macrolide antibiotic, azithromycin, leads to erosion of DPPC domains in a fluid DOPC matrix [A. Berquand, M. P. Mingeot-Leclercq, Y. F. Dufrene, Real-time imaging of drug-membrane interactions by atomic force microscopy, Biochim. Biophys. Acta 1664 (2004) 198-205.]. Since this observation could be due to an effect on DOPC cohesion, we investigated the effect of azithromycin on elastic properties of DOPC giant unilamellar vesicles (GUVs). Microcinematographic and morphometric analyses revealed that azithromycin addition enhanced lipid membranes fluctuations, leading to eventual disruption of the largest GUVs. These effects were related to change of elastic moduli of DOPC, quantified by the micropipette aspiration technique. Azithromycin decreased both the bending modulus (k(c), from 23.1+/-3.5 to 10.6+/-4.5 k(B)T) and the apparent area compressibility modulus (K(app), from 176+/-35 to 113+/-25 mN/m). These data suggested that insertion of azithromycin into the DOPC bilayer reduced the requirement level of both the energy for thermal fluctuations and the stress to stretch the bilayer. Computer modeling of azithromycin interaction with DOPC bilayer, based on minimal energy, independently predicted that azithromycin (i) inserts at the interface of phospholipid bilayers, (ii) decreases the energy of interaction between DOPC molecules, and (iii) increases the mean surface occupied by each phospholipid molecule. We conclude that azithromycin inserts into the DOPC lipid bilayer, so as to decrease its cohesion and to facilitate the merging of DPPC into the DOPC fluid matrix, as observed by atomic force microscopy. These investigations, based on three complementary approaches, provide the first biophysical evidence for the ability of an amphiphilic antibiotic to alter lipid elastic moduli. This may be an important determinant for drug: lipid interactions and cellular pharmacology.
膜双层的弹性特性是控制其变形的关键参数，并且可能受到药物制剂的影响。我们之前的原子力显微镜研究表明，大环内酯类抗生素阿奇霉素会导致流体二油酰磷脂酰胆碱（DOPC）基质中二月桂酰磷脂酰胆碱（DPPC）结构域的侵蚀[A. 贝昆德、M. P. 明乔特 - 勒克莱克、Y. F. 迪弗雷内，通过原子力显微镜实时成像药物 - 膜相互作用，生物化学与生物物理学报1664（2004）198 - 205]。由于这一观察结果可能是由于对DOPC内聚力的影响，我们研究了阿奇霉素对DOPC巨型单层囊泡（GUVs）弹性特性的影响。显微电影摄影和形态计量分析表明，添加阿奇霉素会增强脂质膜的波动，最终导致最大的GUVs破裂。这些效应与通过微量吸管吸液技术量化的DOPC弹性模量的变化有关。阿奇霉素降低了弯曲模量（k(c)，从23.1±3.5降至10.6±4.5 k(B)T）和表观面积压缩模量（K(app)，从176±35降至113±25 mN/m）。这些数据表明，阿奇霉素插入DOPC双层中降低了热波动能量和拉伸双层所需应力的要求水平。基于最小能量对阿奇霉素与DOPC双层相互作用的计算机模拟独立预测，阿奇霉素（i）插入磷脂双层的界面，（ii）降低DOPC分子之间的相互作用能，（iii）增加每个磷脂分子占据的平均表面积。我们得出结论，阿奇霉素插入DOPC脂质双层中，从而降低其内聚力，并促进DPPC融入DOPC流体基质，正如原子力显微镜所观察到的那样。这些基于三种互补方法的研究为两亲性抗生素改变脂质弹性模量的能力提供了首个生物物理证据。这可能是药物与脂质相互作用和细胞药理学的一个重要决定因素。
